US2891196A - Alternating current arc welding devices - Google Patents

Alternating current arc welding devices Download PDF

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Publication number
US2891196A
US2891196A US755944A US75594458A US2891196A US 2891196 A US2891196 A US 2891196A US 755944 A US755944 A US 755944A US 75594458 A US75594458 A US 75594458A US 2891196 A US2891196 A US 2891196A
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United States
Prior art keywords
voltage
welding
impulse
circuit
capacitor
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Expired - Lifetime
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US755944A
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English (en)
Inventor
Lisser Jacques
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Willem Smit and Companies Transformatorenfabriek N V
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Individual
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/06—Arrangements or circuits for starting the arc, e.g. by generating ignition voltage, or for stabilising the arc
    • B23K9/073—Stabilising the arc
    • B23K9/0738—Stabilising of the arc by automatic re-ignition means

Definitions

  • the present invention relates to a device for arc welding by means of alternating current comprising a source of alternating current, e.g. a welding transformer, and a composite auxiliary circuit which contains an impulse circuit cooperating with the welding arc and having a capacitor for the periodic supply of voltage impulses across said arc at points of time in the vicinity of those at which the welding current is zero and a loading circuit having an impedance, eg. a choking coil, for periodically loading said capacitor.
  • a source of alternating current e.g. a welding transformer
  • a composite auxiliary circuit which contains an impulse circuit cooperating with the welding arc and having a capacitor for the periodic supply of voltage impulses across said arc at points of time in the vicinity of those at which the welding current is zero and a loading circuit having an impedance, eg. a choking coil, for periodically loading said capacitor.
  • a welding device of this type in which a gas discharge tube operating as a switch is connected in series with the capacitor for the supply of voltage impulses to the impulse or discharge circuit and in which both the capacitor is periodically loaded and the gas discharge tube is periodically ignited by means of a transformer fed with the voltage of the welding arc and having a magnetic core of great permeability and with a relatively small zone of transition between the unsaturated and the saturated condition.
  • This device has some disadvantages, viz. the use therein of a gas discharge tube, that means of a vulnerable and wearing element, and the fact that for loading the capacitor only the very short period is available, in which the magnetic core of the transformer is unsaturated so that for obtaining a predetermined impulse energy a relatively large and expensive transformer is required.
  • the present invention has the object to avoid the disadvantages of the known welding devices and to provide an apparatus in which no discharge tube is used for closing the impulse circuit and nearly the entire half cycle of the feeding voltage is available for loading the impulse capacitor so that much smaller transformers and choking coils sutlce for the supply of a predetermined irnpulse energy. It consists in that provided in the impulse or discharge circuit is a choking coil having a magnetic core of great permeability and with a relatively small zone of transition between the unsaturated and the saturated condition.
  • the present invention makes it possible to connect in cascade a great number of impulse circuits.
  • one or more impulse circuits connected in series having each a capacitor and a choking coil provided with a magnetic circuit of great permeability and with a relatively very small zone of transition between the unsaturated and the saturated condition.
  • Such a cascade connection is able to produce impulses of the same energy as but of smaller duration, that means of greater peak energy, than those produced by a single impulse circuit, whereby said connection will have a smaller output impedance. Consequently, for the production of these short impulses less input energy is required than for the production of impulses of longer duration when a certain peak power is to be given. Owing to the small output impedance the peak voltage will be less affected by the load impedance constituted by the welding transformer,
  • the welding device may be provided with means for the pre-magnetization by direct current of the magnetic core of the choking coil of at least one impulse circuit, so that said magnetic core can only be brought into the saturated condition in one direction by the current passing said choking coil during the loading period of the capacitor.
  • the loading circuit and the capacitor may be so connected and so dimensioned as to constitute together an oscillatory circuit, of which the resonance frequency is equal to the frequency of the source of current.
  • the present invention makes it possible in a simple way to so construct the welding device as to have fired the voltage impulse by the transition of zero of the arc voltage itself.
  • the loading circuit and the impulse circuit must be so interconnected as to ensure that during the loading period of the capacitor the voltage of the latter has the same polarity as the voltage of the arc before passing zero and the choking coil of the impulse circuit must be so dimensioned as to ensure that said coil is unsaturated at each point of time before that at which the arc voltage passes zero and only becomes saturated as a result of the change of polarity of the arc voltage after the latter has passed zero.
  • the voltage of the capacitor will at each time during the transition of zero of the welding voltage, at which point of time the arc is extinguished, be in series with the no-load or feeding voltage which is leading in respect of the welding voltage and at that point of time has already the opposite polarity, so that the voltage across the impulse circuit is suddenly considerably increased and, thereby, the choking coil is immediately brought into the saturated condition and the impulse is produced between the welding electrode and the object to be welded.
  • the loading circuit may be fed by the series connection of the welding winding of said transformer or a part of said winding and a second source of alternating current, of which the voltage is at any time equal and in opposition to the no-load voltage of said welding winding or said part thereof.
  • This second source of alternating current may be a second transformer fed by the feeding voltage.
  • the auxiliary circuit comprising the loading circuit and the impulse circuit or circuits is fed by the fall of voltage in the welding transformer.
  • Figure l a diagram of connections of a rst embodi- Fig. 2 voltage curves for the device shown in Fig. 1;
  • Fig. 3 a diagram of connections of a second embodiment
  • Fig. 4 a diagram of connections of a third embodiment of the present invention.
  • Fig. 5 is a variant of the impulse circuits used in Figs. l, 3 and 4.
  • Figs. l, 3, 4 and 5 the primary and the secondary winding of a welding transformer are designated by 1 and 2, the windings of a loading transformer by 3 and 4,
  • the capacitor 8 is loaded during a halfcycle of the alternating current through the impedance 7. At the same time a magnetizing current ows through the choking coil 9, which current is very small owing to the high permeability. After a certain time the choking coil 9l becomes saturated so that practically no voltage is gen ⁇ erated across said coil any more. In that case the-capacitor 8' is connecte-d almost directly in parallel with the capacitor 8.
  • the impulse circuit 8, 9, 8 which is closed by the saturated choking coil 9 is an oscillatory circuit, in which the energy accumulated in the capacitor 8 ⁇ will swing out with high frequency.
  • the enengy of the capacitor 8 will be transferred to the capacitor 8 of the impulse circuit connected with the arc space.
  • the choking coil 9 will also become saturated and a voltage impulse will be produced across the are space between the welding electrode and the body to be welded.
  • the illustrated cascade connection is not definitely necessary, it has the advantage that the choking coil may be made smaller.
  • the energy accumulated in the capacitor 8 during a half cycle of the feeding voltage is delivered to the are space during a much smaller time. This time is determined by the self-frequency of the oscillatory circuit consisted of the capacittor 8', the saturated choking coil 9 and the arc space. The smaller the inductance of the choking coil 9 is made the higher said self-frequency and the shorter but more intensive the impulse current'will be at an accumulated power which remains the same.
  • the apparatus may be made so as to saturate the choking coil 9 at the point of time at which the welding current is zero.
  • the moment7 of the zero transition of the welding current depends on external conditions such as the adjustment of the welding current and the arc voltage. Said moment may vary during the welding process so that there is a risk that the impulse is produced too early or too late.
  • the loading circuit and the impulse circuit or circuits are so interconnected as to ensure that the Voltage across the capacitor during loading lthereof has the same polarity as the arc voltage before its zero transition.
  • the choking coil of the impulse circuit which is directly loaded by the loading circuit must be so dimensioned as to ensure that said coil is unsaturated at any time before ⁇ the Zero transition of the arc voltage and becomes saturated only as a result of the polarity inversion of said voltage due to the zero transition thereof.
  • the device illustrated in Fig. 1 also produces impulses when the welding apparatus is in its no-load condition. With the aid of the device shown in Fig. 3 it is possible to produce voltage impulses across the arc space between the electrode 5 and the body 6 to be welded only when the welding process is going on.
  • the feeding transformer 3, 4 is fed by the series connection of the secondary winding 2 of the welding transformer 1, 2 and the secondary winding 15 of an auxiliary transformer 15, 16.
  • the secondary winding 15 generates a voltage, which at any time is equal and in opposition to the no-load voltage of the welding transformer 1, 2.
  • the transformer 3, 4 of the loading circuit is fed with a voltage which is proportional to the drop of voltage in the welding transformer during the welding process. At the noload condition said drop of Voltage is nihil, so that the impulse capacitor can not be loaded to a value required for the production of impulses.
  • the choking coil 9 may be provided with an auxiliary winding 17, which is fed through a resistance or a choking coil 18 by a source 19 of direct current.
  • the choking coil 9 may be so pre-magnctized as to ensure that its magnetic core is brought into the condition of saturation in one direction only by the current owing through said coil during the loading period of the capacitor.
  • the voltage impulse is delivered to the arc space parallel to the welding voltage, however, in the device illustrated in Fig. 4 it is produced in series with the welding voltage.
  • an auxiliary transformer 2t) 21 is provided in the impulse circuit, of which the primary winding 20 is connected to the impulse capacitor 8 in series with the choking coil 9 and the secondary Winding 21 is connected to the welding transformer 1, 2 in series with the arc space between the electrode 5 and the body 6 to be Welded.
  • the secondary winding 2 of the welding transformer 1, 2 is shunted by a capacitor 22 for letting the high frequency impulse pass, since otherwise the latter should have to pass through the welding transformer.
  • Fig. 5 illustrates a device in which, ⁇ with respect to the devices shown in Figs. l, 3 and 4, the choking coil 9 with special magnetic core and the impulse capacitor 8 have changed places.
  • a device for arc welding by means of alternating current comprising, in combination, a source of alternating current such as a welding transformer, a capacitor for the periodic supply of voltage-impulses across the welding arc at points of time in the vicinity of those at which the welding current is zero, a choking coil having a magnetic core of great permeability and ⁇ with a relatively small zone of transition between the unsaturated and the saturated condition, said capacitor and said choking coil forming part of an impulseor discharge circuit which cooperates with the welding arc, a circuit for periodically loading said capacitor and an impedance such as a choking coil forming part of said loading circuit, said impulse or discharge circuit and said loading circuit constituting Atogether a composite auxiliary circuit of the Welding device.
  • the device as set forth in claim l, 'which includes a welding transformer in which a second source of alternating current is provided and said loading circuit is fed by the series connection of the Welding winding of said transformer or part of said Winding and said second source, the voltage of said second source of alternating current being at any time equal and in opposition to the no-load voltage of said Welding winding or said part thereof.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Arc Welding Control (AREA)
US755944A 1957-08-28 1958-08-19 Alternating current arc welding devices Expired - Lifetime US2891196A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL220192A NL101869C (pl) 1957-08-28 1957-08-28

Publications (1)

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US2891196A true US2891196A (en) 1959-06-16

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ID=19785344

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Application Number Title Priority Date Filing Date
US755944A Expired - Lifetime US2891196A (en) 1957-08-28 1958-08-19 Alternating current arc welding devices

Country Status (7)

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US (1) US2891196A (pl)
BE (1) BE570308A (pl)
CH (1) CH359494A (pl)
DE (1) DE1079246B (pl)
FR (1) FR1210843A (pl)
LU (1) LU36343A1 (pl)
NL (2) NL101869C (pl)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3231711A (en) * 1963-05-23 1966-01-25 Glenn Pacific Corp Frequency controlled welding arc power supply system
US3609290A (en) * 1968-12-13 1971-09-28 Mark Corp Electric arc control system
US20070102405A1 (en) * 2003-11-25 2007-05-10 Andreas Prinz Method and circuit for contactless ignition of a welding arc with high frequency ignition pulse packets

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4233818C2 (de) * 1992-10-07 1995-01-26 Wilhelm Merkle Schweismaschine Schweißverfahren und -vorrichtung

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB595697A (en) * 1945-05-07 1947-12-12 Robert Ironside Bagnall Improved apparatus for electric arc welding
US2495183A (en) * 1948-11-03 1950-01-17 Westinghouse Electric Corp Arc welding apparatus
FR1008972A (fr) * 1950-01-21 1952-05-23 Dispositif d'alimentation en monophasé des arcs de soudure et appareils analogues
US2784349A (en) * 1951-12-28 1957-03-05 Air Reduction Electric arc welding
GB729745A (en) * 1952-01-22 1955-05-11 Foster Transformers Ltd Improvements in electric arc welding systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3231711A (en) * 1963-05-23 1966-01-25 Glenn Pacific Corp Frequency controlled welding arc power supply system
US3609290A (en) * 1968-12-13 1971-09-28 Mark Corp Electric arc control system
US20070102405A1 (en) * 2003-11-25 2007-05-10 Andreas Prinz Method and circuit for contactless ignition of a welding arc with high frequency ignition pulse packets
US7638734B2 (en) * 2003-11-25 2009-12-29 Fronius International Gmbh Method and circuit for contactless ignition of a welding arc with high frequency ignition pulse packets

Also Published As

Publication number Publication date
CH359494A (de) 1962-01-15
BE570308A (pl) 1958-08-30
NL220192A (pl) 1900-01-01
DE1079246B (de) 1960-04-07
NL101869C (pl) 1962-07-16
FR1210843A (fr) 1960-03-10
LU36343A1 (pl) 1958-10-11

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